Wireless telegraphy by electric waves.



PATENTED FEB. 28, 1905.

A. BLONDEL.

WIRELESS TELEGBAPHY BY ELECTRIC WAVES.

APPLICATION FILED DEG. 3, 1900.

2 SHEETS-$111531 1.

V n n n nAn fl jV 3W 7 mi, (5mm Om 1 Qhmmwm No. 783,923. PATENTED FEB. 28, 1905.

A. BLONDEL. WIRELESS TELEGRAPHY BY ELECTRIC WAVES.

APPLICATION FILED DBO. 3,1900.

2 SHBETS-SHEET 2.

Patented February 28, 1905.

UNITED STATES PAT NT OFFICE.

ANDRE BLONDEL, OF PARIS, FRANCE.

WIRELESS TELEGRAPHY B Y ELECTRIC WAVES.

SPECIFIGATIONforming part of Letters Patent No. 783,923, dated February 28, 1905.

Application filed December 8, 1900. Serial No. 38.539.

My invention has referende to improvements in wireless telegraphy, the object being the selective reception at a given station of a signal or message transmitted from one o'E- a number of transmitting-stations or the simultaneous selective fi-ec'eption at one station of two or more messages coming from two or more transmitting stations.

Prior to my invention it has been attempted to accomplish the selective reception at a re ceiving-station of signals emitted at one of a number of distant transmitting-stations by electrically tuning the receiving mast-wire or the receiving-circuit in unison with the periodicity of the electromagnetic waves emitted at such transmi tting-station. The difficulties encountered in such systems are now well recognized, and they can mainly be traced to the fact that it is practically impossible to obtain accurate syntony between two mast-wires be- 'cause of the enormous frequency of the electromagnetic waves emitted by one and to be selectively absorbed by the other.

In accordance with my invention syntony between the transmitting and receiving mastwires is not aimed at and is not utilized, and electrical tuning of any kind may be dispensed with in accordancewith my invention.

The characteristic feature of the invention herein claimed is to mechanically tune the receiving apparatus in unison with the frequency of groups of electromagnetic waves emitted from a transmitting station or stations, whereby signals coming from different stations are mechanically and not electrically selected by the receiving apparatus, so that no electrical tuning of the receiving mast-wire or of the receiving-circuits becomes necessary, although such tuning, and particularly of the receivingcircuits, is not necessarily excluded.

. In the following description instances of utilizing tuned receiving-circuits as adjuncts to acoustically-tuned receivers are indicated; but this forms no part of the invention herein claimed, since it has been made the subject of a divisional application, Serial No. 164,580, filed July 7, 1903.

In the accompanying drawings, which form a part of this specification, my invention is illustrated as follows:

Figures 1 and 2 are diagrams illustrating the fundamental idea upon which my invention is based as distinguished from the fundamental idea which underlies the procedures heretofore attempted in wireless telegraphy. Figst3 and 4 are diagrams illustrating the equipment of transmitting-stations in accordance with my invention. Figs. 5, 6, 7, and 8 are diagrams illustratingvarions equipments of receiving-stations with acoustically-tuned receivers in accordance with my invention, and Figs. 9 and 10 are diagrams showing the use of electrically-tuned receiving-circuits in conjunction with acoustically-tuned receivers.

In Fig. 1 the curves P Q V indicate electric waves which are produced at the trans-' mitting-station in any ordinary or improved manner by the charges and discharges of an oscillator of the Hertz type and which give rise to corresponding electromagnetic waves which proceed from the mast-wire. It will be seen that these waves occur in groups and that each group is composed of a number of waves which become very rapidly ent'eebled, the first .wave of each group being of com paratively great amplitude and the following waves of each group being rapidly reduced in amplitude by the dampening effects to which they are subjected, so that the periods between the successive discharges of the oscillator comprise intervals in which there are practically no waves emanating from the mastwire, and these intervals of no oscillation form a large fraction of the period between two successive discharges. At the distant station the electromagnet waves arrive considerably 7 receive and respond to no other frequency;

but in accordance .with my invention the receiving-station takes no selective notice of the wave -frequency. It receives waves of all frequencies; but the receivers respond only i 1 5 to the group frequencies of suchwavs, making one movement or one vibration in respouse-to each group of waves. ihis is in- Y dicated in the diagram Fig. 2, where P Q V again represent the wives corresponding to 2o successive discharges of the transmitting-oscillator, and p q '0' represent the correspond- 7 ing successive vibrations of a receiving apparatus say a telephone-diaphragm or a vibratingieed-tuned to the frequency of the I groups P Q V.

.An essential requisite for the practice-of I my invention is that at the transmitting-stations there be a means for producing electrical discharges of the desired frequency or o frequencies and that the discharges be disruptive as distinguished from discharges which merge into each other. It is within my invention to use any of the means alforded by 7 Q -the knownarts to accomplish this result; but 3 5 I have found the equipment diagrammatically indicated in Figs. 3 andtparticularly efiective.

' Q In Fig. 3 is shown an induction-coilT,in the primary of which is a batteryBand any kindof an tomatic circuitbreaker of definite predetero mined "periodicity. The conventional device indicated at Z may represent such breaker,'which may be either arheotomeof the kind ordinarily used in connection with Ruhmkorfi coils or it maybe an electrolytic circuit- 5 breaker or a rotary circuit-breaker of anyordinary or improved kind: In this "primary circuit there is a key I for closing and opening'the circuit. The secondary circuit includes the two oscillator-balls X, set at the 5o proper striking distance, which forms the spark-gap. F rom one of these oscillator-balls extends the mast-Wire A and from the other 7 the ground connection E. An arrangement of this kind has been found in practice to give rather poor results, since the discharges between the oscillator ballsare not distinctly and sharply disruptive, particularly when the periodicity of the circuit-breaker Z is high. It has been found in such cases that the discharges merge into each other and tend to form n and maintain an electric arc. Forthe purposes of my invention the formation of an are at the oscillator is inadmifible, and in order to prevent this} place in the secondary 5 circuit a condenser C of suitable capacity inshunt aroundthe spark-gap. If the interrupterZis-of the electrolytic type, its frequency can be adjusted at will by an ance-coilS of suitable: size included in the?\ primary cuouit or by properly the numberof cells in series forthchatteryll. Theproperfroquoncyisobtainodlyohscrving the rule thatanincreaseof therimberof cells in serim or the. diminution of the impedance ofthecireuitincreasesthefrequcncyof the interruptions, and vice vera.

Thearrangementindicatedinl 'igiissimilartothatinFrg. 3;exceptthatinphceof the interrupterZand thebatteryB, I thereuse an alternating-current dynamo A. -The induction-coil or transformer T-used in this arrangementis sochosen as togivean elevated potential in the secondary eircuitsy anywhere from twenty-five thousnd up to one hundred thouand volts. With such high potentialsthecondensercmustofcoursebeproperlysoasnottobreak downundcr the high presure." Byadjusting the speed and electromotive force of the altermtor the inductance of the by the'selfinductance S andthecapacityof thecondemer G in the secondary circuit thenurnber ofdischargesatthespark-gapcan beadjusted to a nicety. Ifoncetheadjustmentis made, thefrequeucyofdisclnrge at thespark-gap muninsin Iamnotconfinedinthepracticeofmyinvention to the use of the identical arrangements for producing, a definite frequency of dischargesatthe Any. other wellknown or improved means for obtaining this result may for this purpose. All that isrequired is thatthei'ebe v. V i at each'station a difl'crent but fixed number of electrical discharges. The range 1 5 of frequencies practically available in my system-israther wide and depends largely upon the particular receiving apparatus wed in a givencase aswill bepointed outfartheron.

One equipment of a receiving-station-is n dicatedin Fig. 5,]where A is the mast-wire, E the ground, and t a self-restoring coherer included Thiscoherermay be of any of the well-known self-restoring types. 'Inshunt-aroundthecoherer t isthe 5 receivingcircuit a B M b, containingthebattery B and a number of" difierentlytuned monotelephones M'M Mthat is tosy, telephones adjusted to selectivelyrcspondeschto a ditferent frequency of electrical impulses." Such monotelephones may be in the manner set forth in United States Patent to Mercadier, No. 447, 194, dated February 2%,

1891, or in any other approved uunner. I

have here shown the monotelephonesarranged in series in the local receiving-circuit"; but they may justaswellbearrangedinmulfiple.

The equipment of the receiving-station (shown in Fig. 5) is adapted to work in conjunction either with one of three trama'nit- 3 teases ting-stations, such as described with reference to Figs. 3 and 4., or in conjunction with three such stations simultaneously. Suppose three such stations be equipped andthat the frequency of discharges .produced at these stastations be five hundred, seven hundred, and nine hundred, respectively. With such outlying transmitters the three monotelephones at the receiving-station must be adjusted to respond, respectively, to five hundred, seven hundred, and nine hundred electrical impulses per secondthat is to say, while these monotelephones will receive any number of electrical impulses without selection they will respond audibly only to these frequencies and will emit musical notes corresponding to these frequencies. If now at/the transmitting-station which has the frequency five hundred the Morse key I be operated, the mast-wire at that station will emit fivehundred groups of electromagnetic waves per second. These groups of electromagnetic waves will be absorbed by the mast-wire of the receiving-station and the resistance of the self restoring coherer Will be varied with the frequency of the waves emitted at the transmitter, but in the manner indicated in Fig. 1 by the groups of waves p q vthat is to say, the resistance of the coherer, and consequently of the whole receiving-circuit, will be varied a vast number of times; but these variations themselves will periodically decrease and increase five hundred times per second, and variations of current in the receiver-circuit will likewise occur in a decreasing and increasing manner in five hundred groups per second. The single elementary variations of current which occur at the enormous rate of the wave frequency cannot affect any of the telephones in the circuit, and even if they could set the telephone-diaphragms into vibration these telephones could not emit a sound corresponding to that frequency, since this rate of vibration is far beyond the limits ofandibility; but one of the telephones being tunedto the rate of five hundred per second will be acted upon by each group of current variation as by a singlecurrent impulse and will vibrate at that rate and emit a corresponding note. The other monotelephones will receive the same current impulses; but being tuned, respectively, to seven hundred and nine hundred vibrations per second they will emit no sound, or practically no sound. The message, therefore, which is sent from the station which is tuned to live hundred discharges per second will be selectively received and made audible by one of the three monotelephone-receivers at the receiving-station. Similarly a message sent from the transmitting-station tuned to seven hundred discharges per second will be selectively received by another monotelephone, and a message transmitted from the station which is tuned to nine hundred discharges per second will be selectively received by the third monotelephone.

'would receive no other intelligence.

Similarly if two of the transmitting-stations simultaneously send messages, or if all the three transmitting 4 stations simultaneously sent mes sages, they will be selectively received each by one of the monotelephones.

It will be seen that the system is not limited to the use. of three receivers, since a much greater number can be installed in the man-. ner described, and each of them will selectively receive a message from one of the suitably-tuned transmitting-stations.

When monotelephones or tuned reeds are used as receivers and are designed to tell themessage by the notes which they emit, the frequency of the discharges at the transmitters must evidently be below the frequency of acoustical vibrations which produce the highest still audible note, nor must the number of discharges at the transmittingstation have a lower periodicity than that which corresponds to acoustical vibrations which give the deepest still audible note.

The arrangement shown in Fig. 6 is similarto that shown in Fig. 5, except that the circuit which contains the self-restoring coherer t and the battery B contains in this case the elctromagnet of a microtelephonic relay R T of any ordinary or improved construction such, for instance, as that shown in United States Patent to Mercadier and Pierquin, N 0. 622,629, dated April 4, 1899-while the monotelephones M M M are in a local circuit with a battery B, and which local circuit contains the microphonic element of the relay, so that the resistance of that circuit is varied in accordance with the incoming groups of electromagnetic waves which atfect the coherer. The microtelephonic relay is of course not tuned, since it has to respond without selection to all group frequencies towhich the monotelephones are tuned. An obvious variation of this arrangement would be to connect the circuit of the coherer with the local circuit containing the monotelephones by an inductioncoil such as is used in ordinary telephony, and in this case the battery B is of course omitted. In the arrangements so far described the signals are received as musical notes of shorter and longer duration separated by intervals of silence in accordance with the manipulation of the key I of the transmitter, and in this manner messages in accordance with the Morse or any other code may be spelled out and received. If the Morse key is once depressed, and so long as it is kept depressed, the regularly-timed discharges at the sparkgap take place continuously, and a continuous series of groups of electromagnetic waves are transmitted and are received at one of the monotelephones, and the speaking of one such monotelephone would inform the receivingoperator which of the transmitting-stations is now in communication with him; but he When,

however, the transmitting-key is manipulated in accordance with a predetermined code-the Morse code, for instance the correspondingly-tuned monotelephone responds to various" numbers of groups of electromagnetic waves with intermissionsof silence. In other words, by the-conventional manipulation of the transmitting-key the primary groups of electromagnetic waves are assembled into short and long code groups, and the response of the monotelephone to such code groups spells out the message. Y

Instead of monotelephones other electronagnetic receiving apparatus, such as sound ers or Morse recorders or any other kind of recorders, may be used. Such arrangement is illustrated in Fig. 7i In this case the circuit of the self-restoring coherer contains a series of relay-magnets R R R, and these act upon vibrating reeds. which are differently tuned each in unison with one of the group frequencies of a corresponding number of outlying transmitting-stations. These vibrating .reeds are in a local circuit of a battery B,

recorders may be operated simultaneously that is to say, two or more messages may be received simultaneously. With this arrangement of receiving apparatus the group frequency-that is to say, the frequency of dis charges at, the transmitter-rnay be niuch smaller than in the case of monotelephonereceivers or in the case of any other kind of acoustical receivers, since the relay-reeds need not emit a musical note. It is therefore all suflicient if the number of discharges at the transmitter is sufiiciently great to su rely comprise one or two such discharges during the shortest closure of the transmitting-key. The

,destructive effects of sparks at the circuit controlling reeds may be obviated in the usual manner by spark-shuntin g condensers, as is the practice with rheotomes in Ruhmkorfi coils.

The arrangement illustrated in Fig. 8 is similar to that shown in Fig. 7, except'that in this case the circuit of the self-restoring coherer contains an electromagnet of the microtelephonic relay R T, the microphonic element of this relay being in a separate local circuit of a battery B, which contains in series the magnets of the relays R R R.- The tuned reeds of these relays are in operative relation to their respective magnets and are in the local receiver-circuit of the battery B,

B, the i In the same containing the sounders or recorders N in normally open multiple branches, the same as in the apparatus shown in Fig. 7 Here again it will be understood that the microtelephonic relay is not tuned, since it has to respond to all group frequencies designed for reception at this station. I 1

Mechanically-tuned receivers in circuits that are not electricallytuned as hereinbefore described are ordinarily all sufiicient for selective or multiple telegraphy; but in some cases the selectivity of the receivers is rendered more pronounced when they are located in or controlled by electrically-tuned circuits, and the use of such electrically-tuned receiving-circuits as an aid to mechanically-tuned receiving apparatus comes within my invention and is illustrated in Figs. 9 and 10, although thisimprovement is not herein claimed, since it has been made the subject of a divisional application, Serial No. 164,580, filed July 7 1903. In Fig. 9 the mastwireA,- grounded at G, and the self-restoring coherer t are arranged as usual. Th coherer is shunted at the points a b by two ircuits, one containing the battery and the condenser 0 in shunt and the other uctance-coil s, the relay-magnet R,

containing the battery B, the inductance-coil 8, the monotelephone M, and the condenser 0 in shunt. These two circuits are only speci: mens, since more than two such circuits or only one such circuit may be throw-n around the coherer.. These branch circuits are tuned each to a different group frequency by the condensers and inductance-coils. As here shown, the relay-magnet R in one of these branch circuits controlsa vibrating reed tuned in unison with-the circuit of its controllingmagnet and itself controlling the local circuit of the battery B, containing any suitable electromagnetic receiver N, such as a sounder or recorder, while the other branch circuit ope'rates the monotelephone M, tuned in unison with the branch circuit which controls it. In Fig. 10 the mast-wire does not contain the coherer, but contains the primary of a transformer j, the secondary of which is in a local circuit containing the coherer tand a condenser c in shunt, and this condenser has such capacity as to tune this secondary circuit in unison with the wave frequency employed at the receiving-station in conjunction with which it isdesigned to work. Around the coherer tis thrown a branch circuit containing a battery B, 'a relay-magnet R, an inductance-coil s, and acondenser c in shunt. This branch circuit is tuned to the group frequency employedat' the transmitting-station in conjunction with which it is designed to work, and the relaythrough the mast-wire receives;without se-- lection the waves of all frequencies employed at several transmitting-stations, transfers selectively to the tuned secondary circuit only the waves having the frequency employed at one of the transmitting-stations, varying the resistance of the coherer at this rate; but the branch thrown around the coherer and which contains-the battery B beingtuned to the group frequency of the aforesaid transmitting-station will receive electrical variations only at that frequency and will therefore act upon the reed of the relay B only at that rate that is to say, at the same rate to which the reed itself is tuned. In this manner the selectivity of the reed becomes more pronounced, as will be readily understood. It will also be readily understood that in all re- .ceiving-stationslike those shown in Figs. 5, 6,

methods of operation, as well as the apparatus which I have here described for practicingthe same. The methods are, however, not

claimed herein, since the same have been madereceivers, selectively actuated each in accord ance with a different group frequency of electromagnetic waves absorbed at the station, substantially as described.

3. In a system of wireless telegraphy, a receiving-station containing a monotelephonic receiver, selectively actuated in accordance with a definite group frequency of electromagnetic waves absorbed at the station, substantially as described. I

4:. In a system of wireless telegraphy, a receiving-station equipped with a number of dif ferently-tuned monotelephonic receivers, selectively actuated each in accordance with a different group freq uency of electromagnetic waves absorbed at the station, substantially as described.

5. ha system of wireless telegraphy, a receiving-circuit containinga self-restoring coherer, a battery and an electromagnetic device, selectively responsive to variations of current of one definite frequency, substantially as described.

netic devices. each selectively responsive to variations of current of a different frequency than the others, substantially as described.

7. In a system of wireless telegraphy, a receiving-station containing a mast-wire, aselfrestoring .coherer responsive to electromagnetic waves absorbed by the mast-wire, and an acoustically tuned electromagnetic receiver, selectively actuated in accordance with a particular group-frequency of the electromagnetic waves absorbed by the' mast-wire, substantially as described.

8. In a system of wireless telegraphy, areceiving-station containing a mast-wire, a self: restoring coherer responsive to electromagnetic waves absorbed bythe mast-wire, ands. number of acoustically difierently tuned electromagnetic receivers, selectively actuated each in accordance with a different group fre-v quency of the electromagnetic waves absorbed by the mast-wire, substantially as described.

9. In a system of wireless telegraphy, a receiving-station containing in its equipment a number of acoustically diflerently tuned electromagnetic receiving devices,each selectively responsive to electrical variations of a differ- "eut frequency, a relay or relays controlling the receivers and controlled by groups of electromagnetic waves absorbed at the station, substantially as described.

10. A system of multiple wireless telegraphy comprising a number of transmitters each provided with means for producing a different number of groups of electromagnetic waves in the unit of time, a receiving-station provided with a mast-wire for absorbing the transmitted waves, and two or ore signalreceiving apparatus, each mechanically tuned to a different pitch so as to be responsive to one only of the differently-rated groups absorbed by the mast-wire, substantially as described.

11. A system of multiple wireless telegra- I phy, comprising a number of transmitters each ing witnesses.

ANDRE BLONDEL.

Witnesses:

AUGUSTE Bamvmnn, HIPPOLYTE BLONDEL. 

